This invention relates to an optical fibre polariser which attenuates one plane of polarisation of propagating light preferentially with respect to the attenuation of light propagating with the orthogonal plane of polarisation.
One form of optical fibre polariser is known in which polarisation maintaining fibre is wound into a coil in such a way as to provide a noticeably higher bending loss for one plane of polarisation than for the other. The present invention is concerned with an alternative form of polariser in which the manner of achieving selectivity of attenuation between the two planes of polarisation is such that constructions of polariser are possible which include a facility for varying, at least over a limited frequency range, the light frequency at which selectivity occurs, and a facility for altering the strength of that selectivity.